This invention relates in general to linear actuators, such as can be used to convert rotational power into a linear force. In particular, this invention relates to an improved linear actuator that is self-contained and well suited for high load, high speed, and high precision applications.
Electro-mechanical actuators are used in a wide variety of industrial applications such as, for example, machine presses and the like. A typical electro-mechanical actuator includes an electric motor that functions as a source of rotational power to provide torque to a linear actuator mounted adjacent thereto. The linear actuator is configured to convert the torque into a linear force. Linear actuators typically include a lead screw that is supported for rotation within a housing. The lead screw is connected for rotation with an output shaft of the electric motor, such as by a belt and pulley system. A driven nut is supported on the lead screw and has an inner diameter that corresponds with an outer diameter of the lead screw. As the lead screw is rotated relative to the driven nut, the driven nut travels linearly along a length of the lead screw, thereby converting rotational power into a linear force. A ram is secured to the driven nut for movement therewith. An end portion of the ram extends from the housing and is adapted to transfer the linear force to a desired work piece.
To prevent the driven nut from rotating with the lead screw, it is known to provide a pin on the driven nut that extends outwardly therefrom and into a groove that is provided in an inner surface of the housing. As the driven nut travels along the lead screw, the pin engages side walls of the groove to prevent rotation of the driven nut. However, it has been found that such a design may not be optimal for applications involving high press loads, increased ram speeds, or high precision. It is also know to provide an external guidance system on the linear actuator. Such a system may include a plurality of support rods that extend from the housing along a desired path of the ram. A support bracket is secured to an end portion of the ram and adapted to guide the ram along the support rods. However, this configuration typically involves bulky components extending from the linear actuator that may be exposed to undesirable environments. Thus, it would be desirable to provide an improved linear actuator that is self-contained and well suited for high load, high speed, and high precision applications.